The present invention relates to the particle beam irradiation apparatus and particle beam irradiation method used for irradiating affected regions with charged particle beams such as proton or carbon ion beams in order to provide medical care.
Among known medical treatment methods is one in which the affected regions of patients who are suffering from diseases such as cancer are irradiated with proton, carbon ion, or other charged particle beams. The large-scale charged particle beam irradiation apparatus used in this treatment method has a charged particle beam generator, a beam transport system, and a plurality of irradiation devices. A charged particle beam that has been accelerated by the charged particle beam generator reaches selected one of the plural irradiation devices through the beam transport system, and then the beam is emitted from the nozzle of the irradiation device to the affected region of the patient lying on a treatment couch. In general, for such a charged particle beam irradiation apparatus with a plurality of irradiation devices, these irradiation devices are connected to one charged particle beam generator and beams can be transported to a desired irradiation device by changing beam transport system data settings (refer to JP-A-11-501232, for example).
Passive scattering and pencil beam scanning are known irradiation methods. Passive scattering is an irradiation method in which beams are spread by a scattering device and ten shaped to fit to the particular shape of the affected region, and pencil beam scattering is an irradiation method in which the inside of the affected region is scanned with narrow beams (refer to Japanese Patent No. 2833602, for example).